Flower Mound town leaders want to see more information before a plan goes forward to expand the county’s water supply.

The town is contesting a permit by the Upper Trinity Water District to build a Lake Ralph Hall saying it will send water bills soaring.

Mayor Tom Hayden said constructing the lake is estimated to cost anywhere from $274 million to $464 million at a time when the UTWD is already paying off debt service in excess of $200 million.

“If you look at their credit rating by Standards and Poors, it said their credit rating is based solely upon Flower Mound’s ability to pay,” said Hayden.

Hayden said the town’s contract makes up about 42 percent of the UTWD’s customer base and he fears the costs of the new lake will eventually rest on their shoulders, and in the water bills of everyone in Denton County.

“I’m not anti-lake or anti-water,” said Hayden, "but before they build a lake that is going to cost hundreds of millions of dollars, we would like for them to explore if there's a more economical supply of water."

Hayden believes the best source would be for the district to buy more water from the City of Dallas, who they already contract through. He said, like UTWD, Dallas is also working to expand their water supply through a new pipeline, but he said that water would be much less costly than the new lake option.

Hayden said his attempts to get UTWD to look into that option or prove that they have explored other possibilities have only yielded dated documents from the late 90’s.

NBC 5 contacted the UTWD about the town’s concerns and received the following response via email from executive director Thomas Taylor:

“Flower Mound and Upper Trinity have presented our respective cases in a hearing at the State Office of Administrative Hearings (SOAH) in Austin, now awaiting the judges’ report. On advice of legal counsel, it is not appropriate to debate the issues with Flower Mound under these circumstances.”

Thomas did add that Lake Ralph Hall, named for U.S. Congressman Ralph Hall, is a critical project to ensure the future water supplies of UTWD.

On a website dedicated to the project, UTWD states that the State of Texas requires they plan their water supply for 50 years in advance. The latest projection shows their current supply only lasting through about 2030.

“Upper Trinity has considered all feasible options for additional water supplies, including the acquisition of additional water from the City of Dallas,” said Taylor. “Upper Trinity plans to purchase additional water from Dallas when available. Lake Ralph Hall is the right size project for the needs of Upper Trinity and can be completed in time to avoid a future water crisis.”

Hayden feels they need to wait and pay off some of their current debt before starting the Lake Ralph Hall project.

"If they add on supply without having demand for it, we're going to be in a world of hurt," he said.

To gain support for their position, the Town of Flower Mound has released this video online explaining their position on the Lake Ralph Hall Project.

UTWD wants to build Lake Ralph Hall in nearby Fannin County and use a pipeline to carry the water into Denton County to service their 25 members including 21 cities and towns, one utility authority, and three special districts; although not all of those purchase water from the district.

UTWD currently draws water from Lewisville Lake, Ray Roberts Lake, Chapman Lake, the City of Dallas, and water reuse and reclamation to name a few. They said the addition of Lake Ralph Hall would increase their daily water offerings by 30 million gallons, provide major environmental benefits around the North Sulphur River and bring $18 billion in economic benefits to Denton, Dallas, Collin and Fannin counties.

If the SOAH approves the permit UTWD hopes to begin construction on the lake soon as they say it could take 25-35 years to properly develop.